In 2001, the Chinese Ministry of Education issued Guidelines for Preschool Education (GPE) (trial version) to call on early childhood practitioners to use a child-centered and play-based approach to teaching and learning. The guidelines also include mathematics within the science domain and described its standards in a way that significantly lessens the teacher's role as knowledge disseminator. Instead, the guidelines encourage mathematics learning and teaching through play, self-discovery, and problem solving. This qualitative case study examined one kindergarten teacher's implementation of and associated challenges in delivering mathematics lessons from a newly developed integrated provincial curriculum (PC) and the quality of instruction as influenced by using a curriculum that is organized around thematic units. The analysis of the curriculum, ten videotaped lessons, two teacher interviews, and other supporting documents, such as student work and teacher lesson plans, indicated that the teacher encountered difficulties implementing the PC as intended due to a number of factors, including inadequate curricular resources, incoherency of the curriculum design, and a mismatch between the mathematics standards and curriculum goals and the teacher's instructional style and teaching philosophy. As a result, the quality of mathematics instruction was poor, especially in the areas of (1) using effective teaching strategies, (2) providing clear and accurate instruction with a positive attitude, (3) engaging students in sustained interactions with mathematical ideas, and (4) offering on-going assessment and feedback. To close, recommendations for curriculum refinement and professional development are provided.